#include <iostream>
#include <iomanip>
#include <stdlib.h>
#include <stdio.h>
#include <cstring>
#include <cstdlib>
#include <ctime>
#include <algorithm>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <map>
#include <math.h>
#include <bitset>
#include <numeric>
#pragma warning(disable:4996)
#define REP(variable, repeatnumber) for(int variable=0; variable<(repeatnumber); ++variable)
#define FOR(variable, start, end) for(int variable=(start); variable<=(end); ++variable)
#define RFOR(variable, start, end) for(int variable=(start); variable>=(end); --variable)
#define ULL unsigned long long
#define LL long long
using namespace std; // 700B
int n, k;
int tb[6][4];
void kzro(){
int s = 1;
REP(i, n + 1) s += i;
while (1){
if (s % 10 != 0){
printf("%d\n", s % 10);
break;
}
else s /= 10;
}
}
int main()
{
scanf("%d%d", &n, &k);
if (k == 0){
kzro();
}
else if (n == 0 || (n == 2 && k == 3) || (n == 3 && k == 1))
printf("1\n");
else if (n == 1 || (n == 3 && k == 2)) printf("2\n");
else if (n == 2 && k == 1) printf("4\n");
else if (n == 3 && k == 3) printf("6\n");
else if (n == 2 && k == 2) printf("8\n");
else if ((n == 4 || n == 5 ) && k == 1) printf("4\n");
else if ((n == 4 || n == 5) && k == 2) printf("8\n");
else if ((n == 4 || n == 5) && k == 3) printf("5\n");
return 0;
}
